Transition Latent Heat Research Articles

Bio-Based Phase Change Materials for Sustainable Development.

The increasing global population has intensified the demand for energy and food, leading to significant greenhouse gas (GHG) emissions from both sectors. To mitigate these impacts and achieve Sustainable Development Goals (SDGs), passive thermal storage methods, particularly using phase change materials (PCMs), have become crucial for enhancing energy efficiency and reducing GHG emissions across various industries. This paper discusses the state of the art of bio-based phase change materials (bio-PCMs), derived from animal fats and plant oils as sustainable alternatives to traditional paraffin-based PCMs, while addressing the challenges of developing bio-PCMs with suitable phase change properties for practical applications. A comprehensive process is proposed to convert bacon fats to bio-PCMs, which offer advantages such as non-toxicity, availability, cost-effectiveness, and stability, aligning with multiple SDGs. The synthesis process involves hydrolysis to break down fat molecules obtained from the extracted lipid, followed by three additional independent processes to further tune the phase change properties of PCMs. The esterification significantly decreases the phase transition temperatures while slightly improving latent heat; the UV-crosslinking moderately raises both the phase transition temperature and latent heat; the crystallization remarkably increases the both. The future research and guidelines are discussed to develop the large scale manufacturing with cost effectiveness, to optimize synthesis process by multiscale modeling, and to improve thermal conductivity and latent heat capacities at the same time.

Study of B/M phase transition and phase transition properties of annealing-tuned high phase transition latent heat of W-VO2 nanorods

Vanadium dioxide (VO2) can spontaneously regulate solar heat according to the ambient temperature, and has great application potential as a candidate for smart glass. However, its Tc, ΔTc and ΔH cannot be coordinated at the same time, and commercial use is greatly hindered. W-doped VO2 powders were prepared by the hydrothermal method under an argon atmosphere. Nanoflowers, nanorods, and other morphologies of W-doped VO2 were characterized. The test results showed that W doping could reduce the Tc of VO2 to 33.5 °C, ΔTc < 10 °C, and with high ΔH (ΔH ≈ 36.98 J/g). The phase transition behavior and morphology change mechanism of W-doped VO2 were investigated. The transformation of B and M phases was controlled by changing the annealing temperature, and W-VO2(M) powders with good phase transition properties were finally produced to meet the requirements of the practical application of smart glass materials.

An Innovative Azobenzene-Based Photothermal Fabric with Excellent Heat Release Performance for Wearable Thermal Management Device.

Azobenzene (azo)-based photothermal energy storage systems have garnered great interest for their potential in solar energy conversion and storage but suffer from limitations including rely on solvents and specific wavelengths for charging process, short storage lifetime, low heat release temperature during discharging, strong rigidity and poor wearability. To address these issues, an azo-based fabric composed of tetra-ortho-fluorinated photo-liquefiable azobenzene monomer and polyacrylonitrile fabric template is fabricated using electrospinning. This fabric excels in efficient photo-charging (green light) and discharging (blue light) under visible light range, solvent-free operation, long-term energy storage (706 days), and good capacity of releasing high-temperature heat (80-95 °C) at room temperature and cold environments. In addition, the fabric maintains high flexibility without evident loss of energy-storage performance upon 1500 bending cycles, 18-h washing or 6-h soaking. The generated heat from charged fabric is facilitated by the Z-to-E isomerization energy, phase transition latent heat, and the photothermal effect of 420nm light irradiation. Meanwhile, the temperature of heat release can be personalized for thermal management by adjusting the light intensity. It is applicable for room-temperature thermal therapy and can provide heat to the body in cold environments, that presenting a promising candidate for wearable personal thermal management.

High reflectivity and latent heat synergetic TiO2/Cs0.33WO3-PU double-layer materials with zero transmittance

Passive Cooling Technology, as a method of achieving long-term refrigeration without the need for external energy input, has emerged as an alternative to traditional energy-intensive cooling, garnering increasing attention from academia and industry. However, current passive cooling technology faces challenges such as incomplete solar energy reflection, overcooling, and inevitable absorption of solar radiation and surrounding environmental heat. This paper presents a passive cooling bilayer film with latent heat storage capability, composed of a solid–solid phase change polyurethane (PU) matrix with added TiO2 and Cs0.33WO3.TiO2/Cs0.33WO3-PU exhibits minimal solar transmittance, with reflectance and emissivity rates of 84.46 % and 93.08 %, respectively. The solid–solid phase change matrix effectively mitigates overcooling and heat input issues, reducing temperature fluctuations and peaks, and thereby enhancing passive cooling performance. At the phase transition temperature (306 K), TiO2/Cs0.33WO3-PU achieves cooling powers of 113.77 W/m2(day time) and 173.19 W/m2(night time), the temperature can be reduced by 14.3 °C under 100 mW/cm2sunlight. Additionally, TiO2/Cs0.33WO3-PU demonstrates outstanding thermal stability and reliabitity, hydrophobicity, as well as resistance to UV aging. Moreover, it offers the flexibility to adjust the phase transition temperature and latent heat of the solid–solid phase change matrix according to specific environmental conditions. TiO2/Cs0.33WO3-PU combines passive cooling materials with phase change materials, and complements each other’s advantages. TiO2/Cs0.33WO3-PU not only improves the cooling power, but also provides a new solution to the problem of heat input and supercooling of passive cooling materials. TiO2/Cs0.33WO3-PU also provides new possibilities for the application of passive cooling materials in the fields of long-term outdoor building cooling, human heat management, food preservation and electrical equipment cooling.

The latent heat of confined fluids calculated from the Clausius-Clapeyron equation

Monte Carlo simulations of simple Lennard Jones fluids confined in different geometries, sphere, cylinder and slit-like pores are conducted to study the vapour-liquid transition. Phase diagrams, in the temperature-density (T-ρ) and pressure-temperature (P-T) are obtained. For each geometry the coexistence lines are plotted from the clapeyron equation of each systems and a P −T equation is proposed in terms of the critical temperature which works for all the systems. Additionally, the transition latent heat is also evaluated, from the enthalpy calculation obtained directly from the simulation data, and the fluid structure from density profiles.

Acceleration of heat discharge of composite lauric acid using magnetic dopant

Composite phase-change materials (PCMs), consisting of nanoparticle metal or metal oxide suspended in an organic PCM, are considered promising for overcoming the significant drawbacks of organic PCM, particularly their relatively low thermal conductivity. This paper presents an experimental study of the performance of composite PCMs in terms of chemical stability, thermal stability, phase transition temperature, latent heat, thermal conductivity, and viscosity related to freezing characteristics. The composite PCM consists of an organic PCM of lauric acid (LA) and magnetic dopants of Fe3O4 and CoFe2O4 at concentrations of 2, 5, and 10 wt%. The freezing data revealed the time and temperature characteristics related to the beginning of freezing, the end of the solidification process, and the total crystallisation period. For dopant concentrations below 5 wt%, the dopant increased the heat transfer rate and accelerated the solidification process. However, its effectiveness at the highest dopant concentration of 10 wt% was highly dependent on the microstructure of the dopant particles and its effect on viscosity and thermal conductivity. Based on the data analysis, we proposed a maximum dopant concentration of 5 wt% for the optimum performance of the composite LA using a magnetic dopant—dependent on the particle size that determined the interparticle magnetic dipolar interaction. However, compared with previous experimental findings for non-magnetic dopant particles, the composite FA using a magnetic dopant showed a lower thermal conductivity enhancement and lower time savings for solidification.

Green, recyclable and high latent heat form-stable phase change composites supported by cellulose nanofibers for thermal energy management

Efficiently addressing the challenge of leakage is crucial in the advancement of solid-liquid phase change thermal storage composite materials; however, numerous existing preparation methods often entail complexity and high energy consumption. Herein, a straightforward blending approach was adopted to fabricate stable phase change nanocomposites capitalizing on the interaction between TEMPO-oxidized cellulose nanofibers (TOCNF) and polyethylene glycol (PEG) molecules. By adjusting the ratio of TOCNF to PEG and the molecular weights of PEG, TOCNF/PEG phase change composites (TPCC) with customizable phase transition temperature (40.3–59.1 °C) and high phase transition latent heat (126.3–172.1 J/g) were obtained. The TPCC of high-loaded PEG (80–95 wt%) ensured a leakage rate of less than 1.7 wt% after 100 heating-cooling cycles. Moreover, TPCC exhibits excellent optical properties with a transmittance of over 90 % at room temperature and up to 96 % after heating. The thermal response analysis of TPCC demonstrates exceptional thermal-induced flexibility and good thermal stability, as well as recyclability and reshaping ability. This study may inspire others to design bio-based phase change composites with potential applications in thermal energy storage and management of smart-energy buildings, photothermal response devices, and waste heat-generating electronics.

An Experimental Study on the Influence Solution Concentration and Nano-Additives on Cold Storage Performance of Tetrabutylammonium Bromide

Tetrabutylammonium bromide (TBAB) is considered a promising alternative cold energy storage material. Due to the high dissociation heat of phase transition at an atmospheric pressure of 278–293 K, which reaches 200–500 kJ/kg, this substance is considered an effective cold energy storage medium for air conditioning systems. In this paper, the cold storage crystallization process of TBAB solution with different concentrations was tested by conducting experiments and the phase transition’s temperature and latent heat were measured. Finally, the growth characteristics of TBAB hydrate crystals with different concentrations (10%, 20%, 30% and 40%) were analyzed. Considering the cold storage temperature, phase transformation temperature and latent heat, the cold storage effect is the best when 40% TBAB solution is used. Although single substance phase change materials have a long service life, they have problems with low thermal conductivity and high undercooling. Therefore, researchers usually improve the performance of phase change materials by adding other auxiliary materials, thereby enhancing their application prospects. Among these auxiliary materials, adding nano additives to phase change materials can significantly improve latent heat, thermal conductivity and nucleation ability, while also reducing undercooling. Therefore, we studied the influence of different nano-additives (Al2O3, SiC, TiO2 and ZnO) on phase change materials. The composites with excellent properties were screened by cooling step cooling curve and differential scanning calorimeter (DSC). Compared with pure TBAB solution, the phase transition latent heat of the composite phase change materials (PCMs) prepared by adding nanoparticles were significantly increased. The results show that adding nano-SiC into 40% TBAB solution can obtain better performance. This work not only provides reference for the further research, but also a sight to design the phase change materials for the application of new phase change cold storage materials.

Enhancing Thermal Efficiency through the Use of Graphite-Infused Phase Change Materials in Roof Structures to Reduce Building Cooling Demand

This research focuses on the thermal properties of three distinctive paraffin waxes—PCMA, PCMB, and PCMC—each characterized by a specific melting point. The crucial phase transition temperature intervals and latent heat values were examined using differential scanning calorimetry (DSC) in the temperature range of 0 °C to 80 °C. These parameters are pivotal for the effective application of these phase change materials (PCMs) in building envelopes, influencing the overall heat storage performance. The study delved into the development and encapsulation of blends containing both the phase change material (PCM) and graphite. This involves combining the chosen PCM with graphite powder and examining the weight ratios of 10% and 20%. The thermal characteristics of these blends revealed that a 10% ratio of graphite powder proved effective in improving the PCM with graphite. This resulted in a reduced range of melting and solidification temperatures while maintaining the essential chemical structure of the PCM without additives. Furthermore, the practical application of PCM–graphite composites within a building’s envelope was explored, revealing a substantial reduction in heat transfer from the exterior to the interior of the building. This underscores the potential for energy-efficient building designs.

Hydrophobic treatment on hollow glass microspheres for enhancing the flowability of lightweight high-performance cementitious composites

The use of hollow glass microspheres (HGMs) in a low water-to-binder matrix generally hinders the flowability of the composite due to the high water absorption capacity of HGMs. This study investigated the feasibility of improving the flow behavior of lightweight high-performance cementitious composites (L-HPC) by adding microspheres with hydrophobic treatment. The hydrophobic HGMs were prepared with a ball milling method using low-cost stearic acid. The successfully modified hydrophobic HGMs were then used for the preparation of L-HPC. The results show that the production, including milling for 2–8 h with a 4 wt% addition of stearic acid, can convert hydrophilic HGMs into hydrophobic ones, with the water contact angle increasing from 0° to 102–154° (as a function of processing time). The diffraction peaks and phase transition latent heat results also proved the modification of the surface of HGMs with a hydrophobic coating layer. Cement hydration monitoring demonstrated that the hydrophobic HGMs hardly absorbed water and did not show significant wetting behavior during mixing. Since more water was available for cement hydration due to the hydrophobic effect of HGMs, the formation of hydration products and flowability were significantly increased. The presence of stearic acid delayed the contact time between some cement particles and water, thereby slowing down the heat release rate, resulting in the prevention of potential early cracking with the maintenance of high strength exhibition even with the enhanced flowability.

Experimental and numerical investigation of PCMS on ceilings for thermal management

In this study, experimental investigation of phase change materials (PCM) integrated into building on ceilings was assessed for thermal management capabilities by comparing two building test models with and without PCM based on fluctuation in PCM temperatures owing to ambient temperature variations. Commercial organic PCM (OM-30) with a peak melting point of 31.10 C was used as PCM with high-density polyethylene (HDPE) as the encapsulation. Differential scanning calorimeter (DSC) was used to examine the thermophysical characteristics of PCM such as phase transition temperature, latent heat, and specific heat capacity. The various PCM temperature ranges included for the study are (i) Above phase change melting temperature range ii) within Phase Change melting temperature range iii) Proximity to PCM onset melting temperature range iv) proximity to PCM end melting temperature range. Under free-floating ambient Condition, the indoor air temperature was dropped in PCM installed room up to 1.69 °C, 5.79 °C, 2.26 °C, & − 2.87 °C compared to without PCM room for a PCM Melting temperature difference of 8.77 °C,1.55 °C, 1 °C & 0.44 °C respectively. Also, it was divulged that the PCM utilized 3.2%, 31.4%, 6.9%, & 12.27% of the total latent heat energy deployed in order to produce a temperature difference of 1.69 °C, 5.79 °C, 2.26 °C, & − 2.87 °C compared to without PCM room.

Development of palmitic acid-lauryl alcohol as binary eutectic for cold thermal energy storage in buildings indoor thermal comfort application - Thermophysical studies and discharging characteristics

There has been a steep increase in cooling energy requirements in recent years owing to the growing demand for thermal comfort in buildings. Electric peak demand required to meet thermal comfort could be curtailed by integrating the Latent Heat Thermal Energy Storage (LHTES) system with conventional systems, resulting in lower greenhouse gas emissions and savings of precious fossil fuels. This paper focuses on the development of binary eutectic Phase Change Material (PCM) and property analysis to determine its compactness for indoor thermal comfort building applications. The investigated eutectic PCM comprises Palmitic acid (PA) –Lauryl alcohol (LA) in the composition 10:90 and the material is a viable system fitting the intended application. By DSC analysis, the phase transition temperature and latent heat of the eutectic PCM are discovered to be 20.25°C and 155.59 Jg−1, respectively. The present study involves various thermophysical studies including corrosion test, thermogravimetric test, thermal conductivity, FTIR analysis, and automated thermal cycling test to evaluate the long-term feasibility of the TES system. The study pays special attention to the corrosiveness of the developed PA-LA eutectic PCM confirming that stainless steel-316 and aluminium are recommended as ideal materials for the fabrication of heat exchangers with longer life. Further, the experimental discharging characteristic of the developed PCM carried out in a high-performance Vapour Absorption Refrigeration (VAR) chamber highlights the robustness of the developed material in terms of prolonged cooling retrieval duration. The developed system will elevate energy efficiency and curb the cooling energy demand when it is coupled with a conventional cooling system.

Preparation and Thermal Performance of Fatty Acid Binary Eutectic Mixture/Expanded Graphite Composites as Form-Stable Phase Change Materials for Thermal Energy Storage.

A series of fatty acid binary eutectic mixture/expanded graphite (FABEM/EG) composite phase change materials (CPCMs) were prepared by absorbing a liquid FABEM into the EG. The thermal properties, thermostability, and thermoreliability were determined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermal cycling tests, respectively. Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) were used to analyze the chemical structure and microstructure, respectively. Thermal conductivity measurements and heat storage/release experiments were carried out to study the heat transfer performance. The DSC test results show that the phase transition temperatures and latent heat of these CPCMs are in the range of 17.8-55.2 °C and 134.9-176.2 J/g, respectively. FT-IR analysis indicates there is only a simple physical adsorption between EG and the PCM and no chemical reaction occurs. SEM results show that the fatty acid binary eutectic mixtures are well adsorbed in the pores of EG, and EG can provide a certain mechanical strength and prevent phase change materials from leaking. The thermal conductivity measurement and heat storage/release experiment show that the addition of EG greatly improves the thermal conductivities of the CPCMs. TGA test results and thermal cycle tests show that the CPCMs have excellent thermal stability and long-term cycling thermal reliability.

Preparation and characterization of modified activated carbon-based shape stabilized eutectic phase change materials for gypsum composites application

Modified SAT-urea eutectic salts (EPCM) as the phase-change materials were prepared using modifiers such as disodium hydrogen phosphate dodecahydrate (DHPD) and carboxymethyl cellulose (CMC). The support material, hydrophilic modified activated carbon (MAC), was prepared using OP-10 as a hydrophilic modifier. The vacuum impregnation method was used to fabricate the MAC-based shape-stabilized eutectic phase-change materials (SSEPCM). The gypsum-based building materials with thermal storage capacity were obtained by compositing surface-treated SSEPCM and gypsum. The surface contact angle, surface functional group, phase transition temperature, latent heat, phase composition, and microstructure of the SSEPCM were examined using the static contact angle meter, Fourier infrared spectrometer, in-situ infrared spectrometer, differential scanning calorimeter, X-ray diffractometer, and scanning electron microscope. The adsorption capacity of MAC increased first and then decreased with the increase of OP-10 content in the modified solution. When the OP-10 content was 0.3 wt%, the contact angle between the surface of MAC and water reduced to 0°, and the mass fraction of EPCM relative to MAC was 93.1 wt%. The results showed that the OP-10 had a good hydrophilic modification effect on the granular activated carbon. The X-ray diffractometer and differential scanning calorimeter results of SSEPCM indicated that there was no chemical reaction between EPCM and MAC, the phase transition temperature was 32.11 °C, and the latent heat was 103 J/g. The latent heat loss rate of SSEPCM was 5.8 % after 100 thermal cycles, and the number of –OH did not decrease during the heating process of SSEPCM, which showed that SSEPCM had good thermal stability. The flexural and compressive strength values of the SSEPCM/gypsum composites were 2.50 MPa and 7.36 MPa, respectively, when 45 wt% SSEPCM was incorporated into the gypsum matrix, which was sufficient for practical applications. The introduction of SSEPCM could slowly reduce the thermal conductivity and significantly improved the thermal inertia of the composites.

The Thermal Stability of Asymmetric Separated Configurations inside Alloy Nanoparticles: Atomic-Scale Modeling of Pd-Ir Nanophase Diagrams.

Compared to alloy bulk phase diagrams, the experimental determination of phase diagrams for alloy nanoparticles (NPs), which are useful in various nanotechnological applications, involves significant technical difficulties, making theoretical modeling a feasible alternative. Yet, being quite challenging, modeling of separation nanophase diagrams is scarce in the literature. The task of predicting comprehensive nanophase diagrams for Pd-Ir face-centered cubic-based three cuboctahedra is facilitated in this study by combining the computationally efficient statistical-mechanical Free-energy Concentration Expansion Method, which includes short-range order (SRO) with coordination-dependent bond-energy variations as part of the input and with rotationally symmetric site grouping for extra efficiency. This nanosystem has been chosen mainly because of the very small atomic mismatch that simplifies the modeling, e.g., in the assessment of vibrational entropy contributions based in this work on fitting to the Pd-Ir experimental bulk critical temperature. This entropic effect, together with SRO, leads to significant destabilization of low-T Quasi-Janus (QJ) asymmetric configurations of the NP core, which transform to symmetric partially mixed nanophases. First-order and second-order intracore transitions are predicted for dilute and intermediate-range compositions, respectively. Caloric curves computed for the former case yield the NP-size dependent transition latent heat, and in the latter case critical temperatures exhibit a specific scaling behavior. The computed separation diagrams and intracore solubility diagrams reflect enhanced elemental mixing in smaller QJ nanophases. In addition to these diagrams, the revealed near-surface compositional variations are likely to be pertinent to the utilization of Pd-Ir NPs, e.g., in catalysis.

A new correlation model for predicting the melting and boiling temperatures of the Lennard-Jones systems

The Lennard-Jones (LJ) potential function is widely employed in molecular dynamics simulations. In this study, the LJ potentials under different characteristic diameter σ and characteristic energy ε were simulated, and the changes in properties such as number density, total energy, phase transition latent heat, and phase transition temperature were detailed. With the increase of σ, the melting and boiling temperatures of the LJ systems and the thermodynamic temperature range corresponding to liquid decrease, while with the increase of ε, the melting and boiling temperatures and the thermodynamic temperature range of liquid increase. Moreover, the phase transition latent heat hardly changes with the increase of σ, but significantly increases with ε. The number densities at the melting and boiling temperatures are only dependent on σ, and are not nearly influenced by ε. Furthermore, based on a modified Lindemann’s melting criterion, a new empirical correlation model is proposed to predict the melting and boiling temperatures of the LJ systems, where the phase transition points are in good agreement with the experimental values. For the melting point, the absolute error between the formula and the experimental measurement for inert gas and methane is no more than 10 K, and for the boiling point, the absolute error is less than 15 K. By this new presented model, some thermophysical properties of the LJ potential systems can be quickly obtained and evaluated.

Latent heat thermal storage of solid-state phase transition in thermally stabilized hexagonal FeS

Large amounts of heat are required in areas such as food processing and textile industries to maintain equipment in the medium-temperature zone 393–573 K. However, thermal storage materials that work at this temperature are rare. Hexagonal iron sulfide FeS exhibits a solid-state phase transition at 420 K, accompanied by a high entropy change. The quenched FeS is unstable when subjected to a thermal cycling test, and the related entropy change declines. A secondary hexagonal phase with Fe deficiency was confirmed by neutron powder diffractions. Annealing FeS at temperatures slightly higher than Tt can accelerate the formation of the secondary phase. Once the sample is stabilized, the entropy change is no longer changeable. The thermally stabilized FeS sample exhibits a relatively high thermal storage density up to 136 J/cm3. This work suggests a new solid candidate for the application of solid-state phase transition latent heat energy storage in the medium-temperature region.

Eutectic Fatty Acids Phase Change Materials Improved with Expanded Graphite.

Low- and ultra-low-grade thermal energy have significant recycling value for energy saving and carbon footprint reduction. Efficient thermal energy storage technology based on phase change materials (PCMs) will help improve heat recovery. This study aimed to develop a composite eutectic fatty acid of lauric acid (LA) and stearic acid (SA) binary system with expanded graphite (EG). The experimental measured eutectic temperature was 31.2 °C with an LA-to-SA mass ratio of 7:3. Afterwards, 1~15 wt.% EG was composited to the eutectic acid, and the thermophysical properties of the composite PCMs were measured by differential scanning calorimetry (DSC) and transient plane source (TPS) methods. The results demonstrated that the phase transition temperature and latent heat of the composite PCMs were stable when the content of EG was more than 5%, and the thermal conductivity and thermal diffusion coefficient of the composite PCMs (10–15 wt.%) increased by 2.4–2.6 and 3.2–3.7 times compared with the pure eutectic acid, respectively. On this basis, a finned-coil-type reservoir was prepared, and an experimental study of heat storage and heat release performance was carried out. The results showed that the heat storage and heat release effects of the heat reservoir were the best when the EG ratio was 10 wt.%. The heat storage time was reduced by 20.4%, 8.1%, and 6.2% compared with the other three EG ratios, respectively; meanwhile, the heat release time was reduced by 19.3%, 6.7%, and 5.3%, respectively.

Preparation and characterisation of binary eutectic phase change material/activated porous bio char/multi walled carbon nano tubes as composite phase change material

The primary purpose of the current work is to develop, fabricate, and characterise a novel composite phase change material for the medium temperature thermal energy storage systems. The proposed composite PCM is made up of a binary eutectic PCM (LiNO3 + NaCl), a supporting material (activated bio char), and thermal conductivity-improving particles (i.e., multi walled carbon nano tubes). XRD, FTIR, and SEM-EDS analysis was used to determine the chemical stability of the composite PCM samples. Using differential scanning calorimetry (DSC), the thermophysical parameters of the composite PCM samples, such as phase transition temperature and latent heat value, are evaluated. With the addition of activated biochar (A-BC) and multiwalled carbon nano tube (MWCNT) particles, the latent heat value of PCM is reduced, and the thermal conductivity enhancement value is increased to 116.11%. The findings demonstrate that employing A-BC and MWCNT nanoparticles ensures the stability of the eutectic chloride and prevents leak. The corrosion rate of the copper, aluminium, stainless steel, and Inconel 617 were determined by immersing it in pure PCM and composite PCM for 12 weeks. The metal specimens that were inserted in the composite PCM were found to have good corrosion stability.

PTFE Crystal Growth in Composites: A Phase-Field Model Simulation Study.

We investigated, via a phase-field model simulation, the effects of a matrix’s properties and a filler’s characters on the polytetrafluoroethylene (PTFE) crystal growth process in composites under various supercooling degrees. The results show that the supercooling degree has a deciding influence on the crystal growth process. The intrinsic properties of PTFE polymer, such as anisotropic strength and phase transition latent heat, affect the growth rate, orientation, and interfacial integrity of the crystal trunk and the branching of the PTFE crystal growth process. The factors of the PTFE crystallization process, such as anisotropic strength and phase translation interface thickness, affect the uniformity and crystallization degree of the PTFE crystal. In the composites, the biphasic interface induces the crystal growth direction via the polymer chain segment migration rate, of which the degree depends on the shapes of the filler and the PTFE crystal nucleus. According to the results, choosing the low molecular weight PTFE and mixture filler with various particle sizes and surface curvatures as the raw materials of PTFE-based composites improves the crystallization of the PTFE matrix.